next up previous
Next: About this document ...



Consider the square $n \times n$ matrix with the following structure

\begin{displaymath}
A = \left [\begin{array}{cccccccc}
1 & \frac{1}{4 }& 0\ldo...
...ce*{.2in}\frac{1}{n+2} & \frac{1}{n}
\end{array}
\right ]
\end{displaymath}



Solve $Ax = b$ for $b^T = [1,2, \ldots n]^T$ using the following methods:
  1. [I.] Thomas algorithm with computational cost ${\cal O}(n)$
  2. [II.] Steepest descent method
  1. [(a)] Check how different your answers are in (I) and (II) for $n= 10,20,100$.
  2. [(b)] Estimate the wall-clock time to solve the system using (I) and (II).
  3. [(c)] How does the number of iterations increase as $n$ increases in (II) and how does the total work scale.



Please write down your answers clearly and return your lists of codes.



George Karniadakis 2004-11-03